The Injection And Fuel Supply Strategy Co-control To Optimization The Performance Of Diesel Engine Under Transient Operating Condition

Nowadys,people begin to attach the importance of environment,in recent years,people have great impression on Hazy weather,people’s attention shifted to the emission of car.more emission regulations are put into effect.It is a challenge to engine technology.High thermal efficiency and big power are great advantages of diesel engine,but the emission of diesel engine will be increased great when in the transient condition(in this paper is 1600 r/min,5 s,engine load increased from 10% to 100%),when in case with EGR,the emission become more seriously.Under the stringent emission regulations,the technology of EGR is necessary.This paper studies the different circuit EGR influence on engine transient performance,and combine the oil loading strategy and injection parameters strategy,to optimize the transient performance of two stage turbochargeing diesel engine.Reduce the influence of EGR on engine transient emission.The main contents and conclusions of this study are as follows:The first part,the experiment researched the influence of high pressure EGR、low pressure EGR and composite EGR on engine transient performance,through EGR valve control strategy to be the appropriate contrast original machine.And through the oil loading strategy optimization the transient emissions performance of engine.The main conclusion is as follows:1.Composite EGR balancing the advantages of low pressure and high pressure EGR,considering the conveniences of research,the original machine strategy as follow: The low pressure EGR all open in the whole transient process,and high pressure EGR valve open 10%,at 1s shut,then open 10% in 4s.The peak value of soot was 15.4%,and the NOx peak was 468 ppm.2.The two stage tubochargeing engine has a lot intake air in the beginning,the smoke emission is smaller than late period in transient condition because of the decline of AFR.The oil loading strategy can use the point,and increases the temperature in cylinder and the power of exhaust.It can improve oil and gas mixing and cylinder heating atmosphere,and increase the response speed of the turbine.finally achieve the goal of reducing emissions.3.The emission “worsest point” is near the midole-large load under transient operation,and the oil loading rate of the “worsest point” is one of main factors in fluence the transient emissions.” fast-slow – fast” strategy caused only two peak,it prove that the oil loading rate has little influence on engine emission in the heavy load transient late.4."fast-slow –fast” oil loading strategy has the best comprehensive performance,smoke peak is only 9.59% compared with the " EGR-original machine " decline reached 37.73%,NOx emission peak at 478.4 PPM,compared with the " EGR-original machine " has slightly higher,growth is only 1.92%,fuel consumption is almost the same with" EGR-original machine ".In the second part,through the injection strategy to optimize the transient performance of the engine.The main conclusions are as follows:1.The entire rail pressure strategy impact on emissions is small,and it has greater influence on the NOx emission,increase the rail pressure can reduce soot emissions,but will increase NOx emissions,slightly reduce the fuel consumption,incrase rail pressure 10 MPa,is the best strategy.2.The segmental rail pressure strategy has less influence on the smoke emission and NOx emission,but it improve the fuel consumption optimizes the economy of the engine.3.In the process of the transient change injection timing can better match engine combustion boundary,and advance injection timing will worsen combustion,the smoke and NOx emissions rise,delay the timing can reduce the smoke and NOx emissions.Delay the injecton timing 4 ° strategy has the best emission performance,smoke peak is only 7.591%,fuel consumption increased slightly.4.It can effectively reduce the smoke emission with the segmental timing strategy,while NOx emission increases slightly,which is slightly lower than the fuel consumption.The optimization of the optimal strategy is delayed injection timing 4 °before 40% load,and then delayed injection timing 6 °.The peak value of smoke was 5.6135%(63.55% lower than that of " EGR-original machine "),and the peak NOx emission peak was 393.4 PPM(15.94% lower than " EGR-original machine "),which was slightly higher than the fuel consumption(the maximum increase was 11.5%).